will vs. be doing vs. be going to [closed]

Question

Q1. Which is the most natural after "My suitcase is very heavy"?

1. "I’ll carry it for you."
2. "I’m carrying it for you."
3. "I’m going to carry it for you."

Q2. Which is the most natural after "Daniel called while you were out"?

1. "OK. I’ll call him back."
2. "OK. I’m calling him back."
3. "OK. I’m going to call him back."

Q3. Which is the most natural after "Daniel called while you were out"?

1. "Yes, I know. I’ll call him back."
2. "Yes, I know. I’m calling him back."
3. "Yes, I know. I’m going to call him back."

Thanks in advance.

P.S. I've changed "most commonly used" to "most natural" in the above questions.

Answer 1

Q1. (1) would be the normal way to offer help. You might use (2) or (3) to insist if you knew the person well and they were reluctant to accept your help.

Q2. (1) would be the most natural response. To me, (2) and (3) - and the replies in Q3 - carry a slight implication of "Yes, I already know and am intending to call him back".

Answer 2

1, in all of them.

2 suggests that you had already decided to do whatever it was (and in Q1 has a hint of "even if you don't want me to")

3 suggests that you have just decided to do the thing, but choosing it over option 1 suggests there is some particular meaning to this decision: exactly what that is will vary (and tone of voice will be significant). It might be that the decision was difficult or the choice unwelcome; or (for Q3 in particular) it might mean that you'll get round to it some time - or perhaps you won't.